Je suis là! = I'm here (to a teacher who asks if you're present in a more generic sense).

Je suis présent = Je suis là = I'm here. When you mean that the ministers have arrived, are present in the conference room, etc. you'd say that they are present as in "Ils sont là", rather than "Ils sont ici".

Je suis ici = I'm here in a more "location-type" sentence such as I'm sitting in this room, here.

In other words, ici is only used when you speak about location, while là is used for location and for a general meaning. You can compare that simply with the idea of using Я тут vs Я в университете. In one case you specify that you're here, ici, in the other you say you're present at the university.

Hope my little russian knowledge can help you sort of figure out what I mean;